Cook shells in boiling water according to package directions. Drain.,Meanwhile, beat egg in a bowl.,______,Spread 1 cup spaghetti sauce in bottom of a 11 1/2 x 7 3/4-inch microwave-safe baking dish.,Now spoon about 2 tablespoons of cottage cheese mixture into each shell.,Arrange in baking dish in a single layer.,Top with remaining sauce and Mozzarella cheese. Cover and microwave 10 to 12 minutes on High, rotating dish 1/4 turn 3 times until bubbly.